Automatic Rotor Speed Control

ABSTRACT

A movable machine includes an engine, a rotatably-mounted rotor, a rotor driver mounted on a frame supported on a plurality of ground engaging members; a rotor speed sensor and machine ground speed sensor provide a rotor speed signal and machine ground speed signal, respectively, to a controller. The controller is configured to use a current machine conditions parameter to determine an optimal rotor speed and command the rotor drive to adjust the rotational speed of the rotor to the optimal speed. The current machine conditions parameter includes the rotor speed signal, the machine ground speed signal, and cutting depth.

TECHNICAL FIELD

This disclosure relates generally to a system and method for controlling the engine and rotor speeds for optimizing performance and fuel efficiency.

BACKGROUND

Road milling machines include machines such as cold planers and rotary mixers, that is, reclaimers and stabilizers. Such machines generally include a machine frame supported on a plurality of tracks or wheels which adjustably support and transport the machine along the surface of the road to be planed or reclaimed. A rotor or milling head, typically rotatably mounted on the machine frame, facilitates removing road surface from a roadbed. Vertical disposition of the rotor and, accordingly, adjustment of a machine frame with respect to the road surface may be provided by hydraulically adjustable rods that support the machine frame above its tracks or wheels, as in a cold planer, or hydraulic cylinders, as in a reclaimer/stabilizer. In the case of a cold planer, the removed road surface is transported by one or more conveyors to a discharge location such as a truck bed of a dump truck for disposal or recycling. In contrast, in a reclaimer, the road surface is pulverized in place, along with a portion of the existing base materials below the road surface in order to form a new homogeneous base; additives or conditioners may also be incorporated with the pulverized road surface and existing base materials to form the homogeneous base.

The rotor is typically a large rotating barrel having a plurality of teeth or ground engaging cutting tools for removing and grinding the road surface. The rotor is usually enclosed in a housing that shields the surroundings from flying debris and contains the milled material. Many cold planers and reclaimers/stabilizers use an up-cut configuration, in which the rotor rotates in the reverse direction to the drive wheel or tracks. In the case of a cold planer, the reverse rotation of the rotor helps drive the milled material up and onto a conveyor. The rotatable rotor may be mechanically or hydraulically driven.

Cold planers and reclaimers may work under a variety of conditions wherein different rotor speeds could be beneficial or provide operating efficiencies when operating to grind different materials having different hardness. In machines where the rotor is connected directly to the engine via a clutch and belt system, the speed of the rotor cannot be changed independently of the engine speed. In machines where the rotor is coupled to the engine by one or more gearing systems and clutches, the speed of the rotor may be adjusted based upon modifications to the gear selected.

U.S. Pat. No. 8,465,105 to Parker et al., discloses a machine having manual and automatic modes for operation of a cutter drum. When operating in the automatic mode, the speed of the cutter drum is determined based upon the machine ground speed and a pre-set ratio of ground speed to cutter drum speed; alternately, the machine ground speed is determined based upon the chosen speed of the cutter drum, again, based upon a preset ratio of ground speed to cutter drum speed.

SUMMARY

The disclosure describes, in one aspect, a movable machine having a frame supported on a plurality of ground engaging members, an engine, a rotor rotatably mounted relative to the frame, and a rotor driver mounted on the frame and operatively connected to the rotor and the engine to provide rotational movement. The machine further includes a rotor speed sensor, a machine ground speed sensor, and a controller. The rotor speed sensor is disposed and adapted to provide a rotor speed signal indicative of a rotational speed of the rotor, while the machine ground speed sensor is disposed and adapted to provide a machine ground speed signal indicative of a machine ground speed of the movable machine. The controller is configured to use a current machine conditions parameter to determine an optimal rotor speed. The current machine conditions parameter includes the rotor speed signal, the machine ground speed signal, and cutting depth. The controller commands the rotor driver to adjust the rotational speed of the rotor to the optimal rotor speed.

The disclosure describes, in another aspect, a machine including a plurality of ground engaging members, a frame movably supported on the plurality of ground engaging members, a rotor rotatably coupled to the frame, a rotor driver operatively connected to the rotor to provide rotational movement to the rotor, and a controller. The controller is configured to receive a current machine conditions parameter, the current machine conditions parameter comprising a ground speed of the machine, a rotational speed of the rotor, and a cutting depth of the rotor, determine a target rotor speed based on the current machine conditions parameter, and adjust the speed of the rotor to the target rotor speed.

The disclosure describes, in yet another aspect, a method of controlling a rotational speed of a rotatably-mounted rotor in a movable machine. The method is implemented by a controller, and includes determining current machine conditions parameter including machine ground speed and type of material to be cut, determining an optimal rotor speed based upon said current machine conditions parameter, comparing the optimal rotor speed to an actual rotor rotational speed to identify any difference between the actual rotor rotational speed and the optimal rotor speed, and adjusting the actual rotor rotational speed toward the optimal rotor speed if an adjustment of the actual rotor rotational speed is indicated.

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 is a side elevational view of a machine in accordance with the disclosure.

FIG. 2 is an enlarged fragmentary view of FIG. 1, partially broken away.

FIG. 3 is a side elevational view of a machine in accordance with another embodiment of the disclosure

FIG. 4 is a schematic view of an embodiment of a rotor speed control arrangement in accordance with the disclosure.

FIG. 5 is a flowchart for an exemplary method of controlling the speed of a rotor of a cold planer or reclaimer in accordance with the disclosure.

DETAILED DESCRIPTION

This disclosure relates to a mobile machine 6 having a rotatably-mounted roller 8 operated by an engine 10 wherein it is desirable to rotate the rotatably-mounted roller 8 at different speeds. While the arrangement is illustrated in connection with a cold planer 12 having a milling head or rotor 14 and a reclaimer 46 having a milling head or rotor 58, the arrangement disclosed herein has universal applicability in various other types of machines as well. The term “reclaimer” in this detailed description and the appended claims will refer collectively to machines utilized as reclaimers and stabilizers. The term “machine” may refer to any machine that performs some type of operation associated with an industry such as mining, construction, farming, transportation, or any other industry known in the art, wherein the mobile machine 6 includes a rotatably-mounted roller 8 operated by an engine 10. Moreover, two or more rotatably-mounted rollers 8 may be connected to the machine 6, although not illustrated. Such rotatably-mounted rollers 8 may be utilized for a variety of tasks and include, for example, milling heads, cutting barrels, rotors, and others. For the purposes of this disclosure, the term “rotor” will refer to and encompass milling heads, cutting barrels, rotors, and rotatably-mounted rollers utilized in conjunction with a cold planer 12 and with reclaimers 46.

Referring now to the drawings, in which like reference numerals represent like parts throughout the several views, FIG. 1 shows a cold planer 12 in accordance with an embodiment, while FIG. 2 shows a fragmented, detailed view of certain operating portions of the cold planer 12 with a portion broken away. The cold planer 12 is generally of typical construction and includes a frame 18 supported by four (two visible) ground engaging members 20. The orientation and height of the ground engaging members 20 are selectively adjustable relative to the frame 18. While the ground engaging members 20 may be of any appropriate design, in this embodiment, each of the ground engaging members 20 includes a track 22 that is powered in two directions by a hydraulic motor 24. The frame 18 further supports the engine 10 enclosed within an engine enclosure 32 and connected to various mechanical, hydraulic and/or electric systems operating the various portions of the cold planer 12.

Operation of the cold planer 12 can be carried out remotely by an operator, or locally from an operator portion 26. From the operator portion 26, an operator may manipulate various machine control devices such as one or more steering devices 28, as well as operator controls 30 that include various control switches, and the like.

For milling a road surface or working surface 40, the cold planer 12 includes the rotor 14 that is rotatably supported on the frame 18 and configured for powered rotation relative thereto about a rotation axis 34 during operation. The rotor 14 has a generally cylindrical shape and includes at least one cutting tool, here a plurality of cutting tools 36, which are disposed along a peripherally outer portion 38 thereof and contact the ground. The outer diameter of the rotor 14 is defined by the outermost surfaces of the cutting tools 36. In this way, the cutting tools 36 perform cuts as the rotor 14 rotates and the cold planer 12 advances along a working surface 40 to be milled. In the illustrated embodiment, for example, as shown in FIG. 2, the rotor 14 rotates in the direction of the arrow in a counter-clockwise direction as the machine 6 moves in a forward direction towards the right side of the figure. A cutting depth of the rotor 14 can be determined by a height-adjustment mechanism (not visible) disposed between the rotor 14 and the frame 18. In the illustrated embodiment, the cutting depth is controlled by controlling the height of the frame 18 with respect to the working surface 40 by appropriately extending and retracting vertical actuators 42 (FIG. 2) disposed between the ground engaging members 20 and the frame 18.

The rotating rotor 14 may be enclosed within a shield or housing 44 from which an intermediate conveyor 50 extends. During operation, debris milled from the working surface 40 by the rotating rotor 14 is flung or otherwise directed towards the intermediate stage conveyor 50 such that material removed from the working surface 40 can be transported to a final stage conveyor 60 for delivery to a location off the cold planer 12, for example, into a leading truck (not shown), in the customary fashion.

Turning to FIG. 3, there is illustrated a reclaimer 46 according to an embodiment. For the purposes of this disclosure, the reclaimer 46 includes a construction similar to the above disclosed cold planer 12 with the exception of the conveyors 50, 60. That is, the reclaimer 46 does not provide for the transport of the milled working surface 40 to an alternate location.

The reclaimer 46 includes a frame 48 supported by a plurality of ground engaging members 52 that, in come embodiments, may be selectively adjustable relative to the frame 48. In this embodiment, the ground engaging members 52 of the illustrated embodiment include four wheels, two of which are visible. The frame 48 further supports the engine 54. Operation of the reclaimer 46 can be carried out remotely by an operator, or locally from an operator portion 56 from which an operator may manipulate various machine control devices.

The reclaimer 46 further includes the roller or rotor 58 configured for powered rotation about a rotation axis 62 during operation. The rotor 58 has a generally cylindrical shape and includes at least one cutting tool, here a plurality of cutting tools 64, which are disposed along a peripherally outer portion thereof and contact the ground. The outer diameter of the rotor 58 is defined by the outermost surfaces of the cutting tools 64. As with the cold planer 12, the rotor 58 in at least one embodiment may rotate in a direction counter to the direction of movement of the reclaimer 46.

The rotating rotor 58 may be supported on the frame 48 by one or more pivoting arms 66. A cutting depth of the rotor 58 can be determined by a height-adjustment mechanism such as one or more hydraulic cylinders 68 disposed between the frame 48 and the arms 66 to adjust the angle at which the arms 66 are disposed relative to the frame 48. In some embodiments, the cutting depth may be further determined by controlling the height of the frame 48 with respect to the working surface 40. As with the cold planer 12 of FIGS. 1 and 2, the rotor 58 may be enclosed within a shield or housing 70 to limit the movement of debris.

Turning now to FIG. 4, in each of the cold planer 12 and the reclaimer 46, the rotor 14, 58 is rotatably driven by a rotor driver 16, which is mounted on the frame 18, 48. The rotor driver 16 may be of any appropriate design, and may include, for example, a drive train that may include one or more gear trains and clutches (not shown individually), a hydraulic motor, or another appropriate driver. The rotor driver 16 may be operatively connected to the engine 10, 54 by way appropriate arrangement.

In order to control the speed at which the rotor 14, 58 rotates about the rotation axis 34, 62, a controller 90 is provided. The controller 90 receives inputs from and/or provides signals to a variety of devices. For example, the controller 90 may receive inputs from and provide commands to the engine 10, 54, as well as the rotor driver 16. In this way, the controller 90 may control the rotational speed of the rotor 14, 58 by way of the operation of the engine 10, 54 and/or the rotor driver 16.

The controller 90 may additionally receive input from one or more sensors or settings, as well as receive signals from other sources, such as physical characteristics or operating characteristics of the machine 6 or its individual components or systems. Parameters may be calculated from within the controller 90 itself, or received from other sources.

For example, information concerning the physical characteristics of the rotor 14, 58 may be provided to the controller 90, including, for example, type of rotor 14, 58 (e.g., standard rotor, fine milling rotor, soil rotor, asphalt rotor, etc.), diameter of the rotor 14, 58, number of cutting tools 36, 64 mounted about the peripherally outer portion 38 of the rotor 14, 58, cutting tool 36, 64 type (e.g., diamond, carbide) and configuration, level of wear of the cutting tool(s) 36, 64, and the rotational speed of the rotor 14, 58. The information indicative of the physical characteristics of the rotor 14, 58 is shown generally at box 94 in FIG. 4, the information being provided to the controller 90 along rotor physical characteristic signal 95.

The physical characteristics of the rotor 14, 58 may be identified by any appropriate mechanism. In at least one embodiment, information indicative of one or more of such physical characteristics of the rotor 14, 58 may be entered by an operator, for example, by way of the operator controls 30. In at least one embodiment, information indicative of one or more of such physical characteristics of the rotor 14, 58 may be preprogrammed into the controller 90 at the time of manufacture or distribution of the machine 6, or when the rotor 14, 58 is first mounted on the machine 6.

In at least one embodiment, one or more appropriate sensors 96 may be provided that sense one or more of the diameter of the rotor 14, 58, the number of cutting tools 36, 64 mounted about the peripherally outer portion 38 of the rotor 14, 58, the cutting tool 36, 64 type, and/or the level of wear of the cutting tool(s) 36, 64, and provide a signal indicative of the rotor characteristics to the controller 90. For example, at least one wear sensor 96 may be provided. The wear sensor 96 may be disposed to sense cutting tool wear, and adapted to provide a cutting tool wear signal 97 to the controller 90. In one embodiment, the wear sensor 96 may be a sensor detecting a machine operating parameter such as an incremental increase in the power required to rotate the rotor 14, 58 over time as an indication of cutting tool wear. In another embodiment, the wear sensor 96 may include an estimator function that estimates a wear factor of the cutting tools based on operating time since a cutting tool replacement. It will be appreciated that each of these options may likewise exist in a single embodiment, that is, the information indicative of the level of wear of the cutting tool(s) 36, 64 may be preprogrammed during manufacture, but may be overridden by the customer, the operator, or an alternate signal from an appropriate sensor.

Information indicative of the operating characteristics of the rotor 14, 58 may likewise be provided to the controller 90. In at least one embodiment, a rotor speed sensor 98 may be disposed and adapted to provide a rotor speed signal 99 that is indicative of a rotational speed of the rotor 14, 58.

Information may likewise be provided regarding the operating characteristics of the machine 6. The controller 90 may calculate or receive information indicative of the cutting depth 100 of the rotor 14, 58 at cutting depth signal 101. As explained above, the cutting depth 100 may be determined based upon the operation of a height-adjustment mechanism (such as hydraulic cylinders 68 in FIG. 3; not visible in FIGS. 1 and 2) disposed between the rotor 14, 58 and the frame 18, 48, or operation of the retracting vertical actuators 42 (FIG. 2) disposed between the ground engaging members 20, 52 and the frame 18, 48. Alternatively or additionally, an appropriate sensor may be provided to sense cutting depth 100.

One or more machine ground speed sensors 102 may be disposed to sense the ground speed of the machine 6. The ground speed sensor 102 may provide a machine ground speed signal 103 indicative of ground speed of the machine 6 to the controller 90. In at least one embodiment, the controller 90 may determine the ground speed based upon rotational speed of the ground engaging members 20, 52 and appropriate dimensions of the ground engaging members 20, 52.

Similarly, a material type signal 105 indicative of the type of material to be cut 104 to be cut may be provided to the controller 90. That is, a material type signal 105 representative of the type of material 104 of the working surface 40 may be provided to the controller 90. In at least one embodiment, as with information concerning the physical characteristics of rotor 14, 58 (see box 94), the material type signal 105 may be set as a default during manufacture or distribution, entered by the customer, or entered by the operator.

In at least one embodiment, one or more particle size sensors 106 may be disposed to sense cut particle size. The particle size sensors 106 may operate using a light or other electromagnetic radiation to measure or otherwise determine an average size of particles that are passing in front of a sensor emitter/receiver pad or camera with digital processing. It will be appreciated that any other appropriate particle size sensor 106 known in the art may be used. The particle size sensor 106 provides a cut particle size signal 107 indicative of, for example, the average size of cut particles resulting from the operation of the rotor 14, 58 to the controller 90.

In at least one embodiment of a cold planer 12, a cut pattern sensor 108 may be provided to sense the cut pattern resulting from operation of the rotor 14, 58. The cut pattern sensor 108 may be of any appropriate design known in the art. The cut pattern sensor 108 may provide a cut pattern signal 109 to the controller 90.

According to an aspect of this disclosure, the controller 90 may be configured to use current machine conditions including current machine operating conditions and/or physical characteristics as identified in a current machine conditions parameter 110 to determine an optimal rotor speed. In at least one embodiment, the current machine conditions parameter 110 includes each of a ground speed of the machine 6, a rotational speed of the rotor 14, 58, and a depth of the rotor 14, 58. In at least one embodiment, the current machine conditions parameter 110 includes the rotor speed signal 99, the machine ground speed signal 103, and the cutting depth signal 101. In this way, for example, as the ground speed of the machine 6 increases, the rotational speed of the rotor 14, 58 may be automatically increased. Similarly, as the cutting depth or the rotor 14, 58 increases, the speed of the rotor 14, 58 may be decreased. The controller 90 may then provide a signal to the rotor driver 16 and/or the engine 10, 54 to adjust the speed of the rotor 14, 58 toward the optimal rotor speed.

Other current operating conditions or physical characteristics may be included in the current machine conditions parameter 110, as shown, for example, in FIG. 4. In at least one embodiment, the current machine conditions parameter 110 may include information concerning the operating parameters or physical characteristics of the rotor 14, 58, including, for example, diameter of the rotor 14, 58, number of cutting tools 36, 64 mounted about the peripherally outer portion 38 of the rotor 14, 58, cutting tool 36, 64 configuration, cutting tool 36, 64 type, a material from which at least one cutting tool 36, 64 is formed, and level of cutting tool wear 36, 64 by way of, for example, a cutting tool wear signal 97. In at least one embodiment, the current machine conditions parameter 110 may include the type of material 104 to be cut that may be provided, for example, by a material type signal 105 that is representative of the type of material 104 of the working surface 40. In at least one embodiment, the current machine conditions parameter 110 may include information reflecting the size of particles cut from the working surface 40, which may be provided, for example, as a cut particle size signal 107. In at least one embodiment of a cold planer 12, the current machine conditions parameter 110 may include information regarding the cut pattern resulting from operation of the rotor 14, which may be provided, for example, as a cut pattern signal 109. In this way, the current machine conditions parameter 110 may be utilized in automatically determining an optimal rotor speed.

According to at least one embodiment, the arrangement may also include an operator rotor command 112 that may be entered by the operator by way of an operator control in the operator portion 26, and provided to the controller 90 as an operator control signal 113. The operator rotor command 112 may be selected by the operator in real time during operation based on a multitude of factors that the operator perceives and determines warrant a change in speed of the rotor 14, 58 including, without limitation, the quality and smoothness of the milled surface, the creation of chips, heating of the rotor cutting tools, noise, dust, roughness of the milling operation, and other factors. Upon determination of an optimal rotor speed based upon the current machine conditions parameter 110, the operator may adjust the optimal rotor speed slightly faster or slower based upon the operator's own experience. The adjustment may be made by any appropriate arrangement. For example, the operator may utilize operator controls 30 including adjustment of a speed dial, slide or arrows on a touch pad. The adjustment of the optimal rotor speed may be calculated by any appropriate mechanism, such as an adjustment defined as a percentage increase or decrease of the determined optimal rotor speed. The controller 90 may provide appropriate signals to the engine 10, 54 or rotor driver 16 to adjust the determined rotor speed control adjustment as indicated by the operator control signal 113.

The controller 90 of this disclosure may be of any conventional design having hardware and software configured to perform the calculations and send and receive appropriate signals to perform the disclosed logic. The controller 90 may include one or more controller units, and may be configured solely to perform the disclosed strategy, or to perform the disclosed strategy and other processes of the mobile machine 6. The controller 90 may be of any suitable construction, and may include a processor (not shown) and a memory component (not shown). The processor may be microprocessors or other processors as known in the art. In some embodiments, the processor may be made up of multiple processors. In one example, the controller 90 comprises a digital processor system including a microprocessor circuit having data inputs and control outputs, operating in accordance with computer-readable instructions stored on a computer-readable medium. Typically, the processor will have associated long-term (non-volatile) memory for storing the program instructions, as well as short-term (volatile) memory for storing operands and results during (or resulting from) processing.

The controller 90 may be programmable. The processor may execute computer-executable instructions for controlling one or more of the engine 10, 54 or the rotor driver 16, such as the methods described herein. Such instructions may be read into or incorporated into a computer-readable medium, such as the memory component or provided external to processor. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to rotor methods for control of the engine 10, 54, or the rotor driver 16. Thus, embodiments are not limited to any specific combination of hardware circuitry and software.

The term “non-transitory computer-readable medium” as used herein refers to any medium or combination of media that participates in providing instructions to processor for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks. Volatile media includes dynamic memory. Transmission media includes coaxial cables, copper wire and fiber optics.

Common forms of non-transitory computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, or any other medium from which a computer or processor can read.

The memory component may include any form of computer-readable media as described above. The memory component may include multiple memory components.

The controller 90 may be enclosed in a single housing. In alternative embodiments, the controller 90 may include a plurality of components operably connected and enclosed in a plurality of housings. The controller 90 may be an integral part of a control panel (not shown). In another embodiment, the controller 90 may be fixedly attached to the frame 18, 48 on in another location. In still other embodiments the controller 90 may be located in a plurality of operably connected locations including being fixedly attached to the frame 18, 48, the engine 10, 54, and/or remotely.

The controller 90 may be communicatively coupled to the engine 10, 54, the rotor driver 16, and/or the drive train through the at least one signal output port. The controller 90 may be communicatively coupled to the sensors, controls, controls, and other inputs to receive respective signals indicative of the respective parameter.

INDUSTRIAL APPLICABILITY

This disclosure relates to a mobile machine 6 having a rotatably-mounted roller 8 operated by an engine 10, 54 wherein it is desirable to rotate the rotatably-mounted roller 8 at different speeds. The disclosure may provide a system and method that may provide efficiencies in operation of a rotor 14, 58 that may enhance mileage, prolong rotor life, reduce down time, and/or reduce operating costs.

Turning now to FIG. 5, there is illustrated an exemplary method 118 according to this disclosure. Referring to box 120, the controller 90 considers current machine conditions parameter 110 including current operating conditions and physical characteristics. The current machine conditions parameter 110 may include, for example, machine ground speed (box 122), a rotational speed of the rotor 14, 58 (box 123), and a cutting depth of the rotor (box 124). In further embodiments, the controller 90 may consider the current machine conditions parameter 110 that may include, for example, cut pattern (box 125) in the case of a cold planer 12, cutting tool type (box 126), cutting tool wear (box 127), material to be cut (box 128), cut particle size (box 129), and type of rotor (box 130). As explained above, the current machine conditions may be determined by any number of mechanisms including, for example, one or more sensors, entries, or calculations based upon various running conditions, sensors and entries.

The controller 90 then determines the optimal rotor speed (box 136) based upon the current machine conditions parameter 110 exemplified by boxes 122-129. In at least one embodiment, in determining the optimal rotor speed, the controller 90 may additionally consider an operator rotor command entered by the operator (box 142).

The optimal rotor speed determined at box 136 is then compared with the actual rotor rotational speed (box 123) determined, for example, by the rotor speed sensor 100 or a calculated rotor speed (see box 138). A determination is then made whether it is desirable to modify the speed of the rotor 14, 58 toward the optimal rotor speed.

In at least one embodiment, the determination of whether it is desirable to modify the speed of the rotor 14, 58 toward the optimal rotor speed (box 138) may include a comparison to a predetermined or preset threshold difference in actual and optimal rotor speed. For example, if the difference between the actual and the optimal rotor speed is greater than a preset threshold numerical value or a given percentage, such as, for example 10% of the optimal rotor speed, an adjustment is made to the rotor speed. It will be appreciated that this threshold difference may be other than a preset numerical value or a percentage and may be dependent upon the machine 6 utilized. If the rotor speed is equal to the optimal rotor speed, or below a threshold difference, then the cycle begins again at box 120, determining operating conditions. On the other hand, if the rotor speed is not equal to the optimal rotor speed, or below the threshold difference, then the controller 90 sends an appropriate command to adjust the rotor speed (box 140).

While the foregoing description provides examples of the disclosed system and technique, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated. 

We claim:
 1. A movable machine having a frame supported on a plurality of ground engaging members, the machine comprising: an engine; a rotor rotatably mounted relative to the frame, a rotor driver mounted on the frame and operatively connected to the rotor and the engine to provide rotational movement, a rotor speed sensor disposed and adapted to provide a rotor speed signal indicative of a rotational speed of the rotor, a machine ground speed sensor disposed and adapted to provide a machine ground speed signal indicative of a machine ground speed of the movable machine, a controller configured to use a current machine conditions parameter to determine an optimal rotor speed, the current machine conditions parameter including the rotor speed signal, the machine ground speed signal, and a cutting depth of the rotor, wherein the controller commands the rotor driver to adjust the rotational speed of the rotor to the optimal rotor speed.
 2. The movable machine of claim 1 wherein the current machine conditions parameter includes at least one of a type of material to be cut and a cut pattern.
 3. The movable machine of claim 1 wherein the rotor includes at least one cutting tool and the current machine conditions parameter further includes information indicative of the cutting tool.
 4. The movable machine of claim 1 further including an operator control adapted to provide an operator control signal indicative of an operator rotor command to the controller, and the current machine conditions parameter further includes the operator control signal.
 5. The movable machine of claim 3 further including at least one wear sensor disposed to sense cutting tool wear and adapted to provide a cutting tool wear signal to the controller, and the current machine conditions parameter further includes the cutting tool wear signal.
 6. The movable machine of claim 1 further including at least one particle size sensor to sense cut particle size and to provide a cut particle size signal to the controller, and the current machine conditions parameter further includes the cut particle size signal.
 7. A method of controlling a rotational speed of a rotatably-mounted rotor in a movable machine, the method being implemented by a controller and comprising: determining current machine conditions including machine ground speed and type of material to be cut, determining an optimal rotor speed based upon said current machine conditions, comparing the optimal rotor speed to an actual rotor rotational speed to identify any difference between the actual rotor rotational speed and the optimal rotor speed, and adjusting the actual rotor rotational speed toward the optimal rotor speed if an adjustment of the actual rotor rotational speed is indicated.
 8. The method of claim 7 wherein the step of comparing includes comparing the difference to a preset threshold difference, and the step of adjusting includes adjusting the rotor speed when the difference is greater than the preset threshold difference.
 9. The method of claim 7 wherein the step of determining current machine conditions includes sensing at least one of the following: machine ground speed, material type, cut particle size, machine height, cutting tool type, rotor wear.
 10. The method of claim 7 further including providing at least one of a material type signal indicative of the type of material to be cut and a cut pattern signal indicative of a cut pattern to the controller.
 11. The method of claim 7 wherein determining the current machine conditions includes determining cutting tool type, the method further including providing a cutting tool type signal indicative of the cutting tool type to the controller.
 12. The method of claim 7 further including providing an operator control signal indicative of an operator rotor command to the controller.
 13. The method of claim 7 wherein the step of determining current machine conditions includes at least one of determining at least one physical characteristic of the rotor, and determining a cutting depth of the rotor.
 14. The method of claim 13 wherein determining at least one physical characteristic of the rotor includes programming at least one of an outer diameter of the rotor, a rotor type, a cutting tool configuration, a material from which the at least one cutting tool is formed, and cutting tool wear into the controller during set up.
 15. The method of claim 7 wherein adjusting the rotor speed includes at least one of adjusting a speed of an engine operatively connected to the rotor, adjusting an operating gear of a gear train operatively connected to the rotor, and adjusting a hydraulic rotor drive motor operatively connected to the rotor.
 16. A machine comprising: a plurality of ground engaging members, a frame movably supported on the plurality of ground engaging members, a rotor rotatably coupled to the frame, a rotor driver operatively connected to the rotor to provide rotational movement to the rotor, a controller configured to: receive a current machine conditions parameter, the current machine conditions parameter comprising a ground speed of the machine, a rotational speed of the rotor, and a cutting depth of the rotor; determine a target rotor speed based on the current machine conditions parameter; and adjust the rotational speed of the rotor to the target rotor speed.
 17. The machine of claim 16 further including: a rotor speed sensor disposed and adapted to provide a rotor speed signal indicative of the rotational speed of the rotor, a ground speed sensor disposed and adapted to provide a ground speed signal indicative of the ground speed of the machine.
 18. The machine of claim 17 wherein the rotor includes at least one cutting tool and the current machine conditions parameter further includes information indicative of a cutting tool type, the machine further including at least one of a cutting tool type sensor disposed to sense the cutting tool type and provide a cutting tool type signal, and an operator control adapted for entry of the cutting tool type and provision of an entered cutting tool type signal.
 19. The machine of claim 18 further including an operator control adapted to provide an operator control signal indicative of an operator rotor command to the controller, and the current machine conditions parameter further includes the operator control signal.
 20. The machine of claim 18 further including at least one wear sensor disposed to sense cutting tool wear and adapted to provide a cutting tool wear signal to the controller, and the current machine conditions parameter further includes the cutting tool wear signal. 